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THE AMERICAN NATURALIST [Vol. XLIV 



F. M. Webster, in the Annals of the Entomological Society of 

 Ah) erica, for June, 1909. Previous experiments with lysiphlebus 

 had indicated that parthenogenetic eggs invariably gave rise to 

 males. Webster and his assistants, however, report varying 

 results. Females of lysiphlebus, reared in isolation to prevent 

 t'i'ililizat ion. were placed with toxoptera which had been raised 

 under cover to preclude previous parasitism. Of 48 such fe- 

 males, 44 produced only males ; the other four produced females 

 also. The few females from these last four parents were allowed 

 to lay eggs under the same conditions; two of the families gave 

 only males, the other two again produced some females. In the 

 third generation one of these two families ran all to males, and 

 in the fourth generation the remaining family gave only males. 



Similar evidence is given by S. J. Hunter in "The Green Bug 

 and its Enemies," Bulletin of the University of Kansas, Vol. 

 IX., Xo. 2, October, 1909. The experiments were carried out 

 by P. A. Glenn and Miss McDaniels, and the usual precautions 

 were taken to prevent fertilization of lysiphlebus and parasitism 

 of the aphids. While some families included only males, others 

 had a small percentage of females. Of an aggregate of 352 

 individuals reared from parthenogenetic eggs, 339 were males, 

 13 females. Later generations seem not to have been bred from 

 any of these females. Among other individuals from parents 

 which may or may not have been fertilized, 34.5 per cent, were 

 males. 



A. Franklin Shull. 



